Quantum Mechanics & Electronic Structure of an Atom

Question 1

What is Quantum Mechanics?

Answer 1

A theory that applies to submicroscopic particles of matter like e.

Question 2

What is the De Broglie Relation?

Answer 2

The wavelength of a particle of mass m and velocity v, is given by,
wavelength = h/mv

Question 3

Can de Broglie relation be directly applied to an electron or atom?

Answer 3

It quantitatively only applies to particles in a force free environment.
Therefore cannot be directly applied to an e where it is subjective to the attractive force of the nuclues.

Question 4

What does Shrödinger’s equation give?

Answer 4

A wave function (psi)- gives information about a particle in a given energy level.
(psi^2 gives the probability of finding the particle within a region of space)

Question 5

What does Heisenberg’s uncertainty principle say?

Answer 5

It is impossible to know, with absolute precision both the position and the momentum of a particle such as an e.

Question 6

What is an orbital?

Answer 6

Region in space where there is a 90% probability of finding an e.
(a mathematical function describing the location and wave like nature of an electron.)

Question 7

What are quantum numbers?

Answer 7

According to quantum mechanics, each e is described by 4 quantum numbers.
They are used to characterize atomic orbitals.
1) n - principal qn (Energy)
2) l - angular momentum qn (Shape)
3) ml - magnetic qn (Orientation)
4) ms - spin qn (Magnetic spin)

Question 8

Draw radial wave functions and radial distribution functions for 1s, 2s, 2p, 3s, 3p, 3d
Compare the difference between radial wave of 1s and 2s.

Answer 8

Draw

Question 9

Define;

1) Electron configuration
2) Orbital diagram

Answer 9

1) A particular distribution of electrons among available subshells of an atom.
2) Shows how the orbitals of an atom are occupied by electrons.

Question 10

What are the rules in filling orbitals? Name and define. (3)

Answer 10

1) Pauli exclusion principle : no two electrons can have the same four qn.
2) Hund’s rule : the lowest energy arrangement of e in a subshell is obtained by putting e into separate orbitals of the subshell before pairing up.
3) Aufbau principle : a scheme used to reproduce the GS e configurations by filling subshells with e in a particular order (draw order).